Type bar action



Nov. 15, 1955 T. H. TOEPPEN TYPE BAR ACTION 2 Sheets-Sheet 1 Filed Dec. 26, 1952 INVENTOR. THURSTON H.TOEPPEN ATTORNEY li r Nov. 15, 1955 T. H. TOEPPEN TYPE BAR ACTION 2 Sheets-Sheet 2 Filed Dec. 26, 1952 INVENTOR. THURSTON H.TOEPPEN w ATTORNEY United States Patent TYPE BAR ACTION Thurston H. Toeppen, Hyde Park, N. Y., assignor to International Business Machines Corporation, New York, N. Y., a corporation of New York Application December 26, 1952, Serial No. 327,947

Claims. (Cl. 197--17) This invention relates to typewriters, and more particularly to an optionally selectable repeat, non-repeat action for a typewriter type bar.

It can be appreciated that in some circumstances, it is desirable to provide a repeat action for type bars. For example, industry demands a repeat action for spacing, back spacing, underscoring etc.

With particular reference to electric typewriters, conventional type bar actuating cams are normally equipped with a trip action, which serves to engage the cam with the power roll when an associated key lever is depressed, and also a non-repeat feature which prevents the cam from initiating a repeat stroke when the key lever is held in a depressed position.

In the past, when continuous or repeat type bar operation was required for typewriters, it was accomplished by removing the non-repeat action entirely, so that the actuating cam would continuously initiate a repeat action as long as the key lever is held down. This 'rnethod is not entirely satisfactory because it tends to produce unwanted repetitions.

Some manufacturers of electric typewriters have supplied extra key buttons which can be depressed to provide continuous operation for such typewriter functions as escapement and underscore without interfering with the normal actions of the regular key button. This construction is an improvement in that it prevents unwanted repetitions, but it is also an undersirable complication in that the key board is provided with extra keys and the cost of the machine is consequently increased.

1 It is an object of this invention to provide an improved type bar actuation mechanism wherein repeat or nonrepeat operation of any desired key is optionally selectable by the typist.

It is a further object of this invention, therefore, to provide an improved electric typewriter wherein either repeat or non-repeat type bar action is optionally selectable at'the will of the operator, without providing additional keys.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

Briefly, the objects of this invention are accomplished by providing an improved key bar or key lever having two stages of operation; (1) a normal or single stroke stage which is characterized by the usual key bar travel and pressure on the key button and (2) a repeat stage produced by depressing the key lever beyond the normal stopping point to a repeat position. The second stage of operation is controlled by a preloaded spring whereby the feel of the key board is unchanged for normal typing, while a moderate extra pressure on the key lever will produce repeat operation.

In the drawings:

Fig. l is a side view of the operating structure of a type bar and its associated key bar. r

2,723,740 Patented Nov. 15, 1955 Fig. 2 is a front View of a key bar guide comb.

Fig. 3 is a top elevation, greatly enlarged, of an abutment member cooperating with the guide comb.

Figs. 4, 5 and 6 are side elevations of the type bar structure of Fig. 1 shown in various positions of operation.

Fig. 7 is a side elevation of a portion of the type bar operating structure positioned for repeat operation.

With reference to the drawing, a type bar 1 is shown positioned for operation, in response to depression of a key bar 2, through an interconnecting structure comprising a link 3, a crank arm 4, a cam 5, and an actuating plate 6. The type bar 1 is pivoted about the usual hoopshaped shaft 7 for rotation from a rest position-i. e. from a basket 8, to the platen 9, thereby to effect the imprinting of a character on a work sheet (not shown) in the usual manner.

Crank arm 4 is positioned for pivotal rotation about a transverse shaft 10 which extends across the base of a typewriter. Shaft 10 supports a plurality of crank arms; i. e. one for each type bar. The rotation of crank arm 4 about shaft 10 actuates its associated type bar 1 to rotate the latter aboutshaft 7 through means of the link 3 which interconnects the head 11 of crank arm 4 and an operating lever 12, an integral part of type bar 1. Crank arm 4 is biased by a spring 13 in a direction to restore the crank arm to its normal or rest position, as shown in Fig. 1. The rest position is defined as that position of crank arm 4 which exists when the head 14 of the type bar 1 is in engagement with basket 8.

To elfect pivotal movement of the crank arm 4 about shaft 10, cam 5, which has a serrated tread 15, is mounted for angular movement on a pivot or shaft 16 supported by the crank arm 4. A cam spring 17 extends between a loop 18 on the cam 5 and an ear 19 on the crank arm 4 for biasing cam 5 normally counterclockwise to the disengaged position shown in Fig. 1. In this position, the serrated tread 15 is just out of engagement with the periphery of a power roll 20 which is incidentally driven by some motor source for rotation at a constant rate in a counterclockwise direction. (Fig. 1).

The serrated tread 15 of cam 5 is eccentric with respect to pivot 16, and accordingly, when the tread is brought into engagement with power roll 20, a frictional drive is obtained between the peripheral surface of the power roll and the serrated tread, causing the cam 15 to swing upwardly and clockwise about the pivot 16, thereby forcing the latter outwardly from the power roll and clockwise about stud 10. This clockwise movement of stud 16 naturally rotates crank arm 4 about shaft 10 to actuate the type bar 1. The length of the serrated tread that engages the peripheral surface of the power roll 20 controls the duration of the direct drive of the type bar 1; that is, it controls the height to which the type bar will be driven under direct power. During the rest of the type bar motion towards the platen 9, i. e. after direct drive ceases, the type bar is in free flight and travels under its own momentum.

During a print stroke, the type head 14 is moved towards the platen 9 as the stud 16 is forced away from the peripheral surface of the power roll 20. When the stud 16 is removed from the peripheral surface a distance greater than the radial distance from the stud to the point on the serrated tread 15 lying in a line joining the centers of the power roll and stud 16, then the frictional drive between the power roll and the serrated tread ceases, and the spring 17 acts to rotate the cam counterclockwise about stud 16 to its normal or rest position relative to crank arm 4. This disengagement between the tread and power roll 20 always takes place before a type head strikes the platen, consequently, as a type bar returns to its rest position, the spring 17 holds the cam out of engagement with the powerrolland a print stroke is complete when type head 14 strikes basket 8.

In a preferred embodiment, cam 5 has a tail piece 21 which is engageable with a control stop 22 to limit the rotation of the cam about stud 16. The purpose of this is to limit the direct drive of a type bar, and consequently the force with which the type head 14 strikes a platen 9. When the tail piece 21 comes in contact with the control stop, the direct drive of the type bar ceases and the type bar must then continue under its momentum to strike the platen. In effect, the engagement of the tail piece 21 with control stop 22 limits the rotation of the cam 5 about stud 16, thereby preventing any surface of greater radius of the serrated tread from coming into contact with the peripheral surface of the power roll 20, and accordingly, the direct drive of the type bar ceases. It might appear that this engagement would also prevent any further movement of the type bar 1, but actually, tail piece, when it engages control stop 22, slides laterally along one of the stop surfaces away from the power roll until the cam is free. The spring 17 then rotates the cam counterclockwise about stud 16 to its retracted or normal position out of engagement with power roll 29. The type bar, however, travels in free flight from the instant that the tail piece 21 strikes the control stop 22.

In order to initiate a type bar print stroke, the serrated tread must be brought into engagement with the peripheral surface of the power roll 20. In the dis closed embodiment, an actuating plate 6 is employed teinitiate tread engagement. The plate is supported for both pivotal and sliding motion with respect to a stud 23 which is carried by the crank arm 4. Specifically, the actuating plate 6 is provided with an elongated or generally elliptical aperture 24 for mounting on stud 23 and simultaneously move downwardly to the right, as indicated in Fig. 1, a distance equal to the difference in the transverse or long diameter of the aperture 24 and the diameter of stud 23. The purpose of this sliding movement will be hereinafter explained. A plate spring 25 interconnected between an ear 26 on crank arm 4 and an ear 27 on the plate 6, normally pulls the actuating plate 6 upwardly into the position shown in Fig. 1. It is to be noted that the car 26 serves the dual function of supporting an end of the spring 25 and of guiding the movement of the actuating plate 6; that is, it limits clockwise movement of the plate about stud 23, and it helps guide the lateral movement of the plate 6 under the influence of spring 25.

The actuating plate 6 is provided with a cam car 28 positioned for engagement with an actuating or camming surface 29 on the cam 5. It is readily apparent that any rotation of the actuating plate 6 about its support stud 23 will cause the cam ear 28 to push on camming surface 29, thereby rotating cam 5 on stud 16 clockwise to force the serrated tread 15 into engagement with the periphery of the power roll 20.

In order to rotate plate 6, an operating lug 30 is positioned on the key bar 2 for engagement with a key ear 31 carried by the actuating plate 6. The key bar is supported for rotation about a shaft 31a, and any clockwise, angular movement of the key bar about support shaft 31a causes lug 30 to act on key ear 31 to rotate the plate 6 about its pivot 23 for actuating the cam 5 so as to bring the serrated tread 15 into engagement with the peripheral surface of the power roll 20, thus actuating type bar 1 for a print stroke.

The shaft 31a which supports the key barsthere being one key bar for each type barextends transversely across the typewriter. Each key bar has a button stem 32, and a finger button 32a. By changing the position of the stem 32; that is, by locating it along the length of the key bar 2 at any one of four positions, the normal typewriter keyboard is obtained. The outer end of each key is supported for controlled movement in a guide comb or cage 33 which is provided with a plurality of guide slots 34, each having a length great enough to permit the desired pivotal movement of a key bar for actuating its assigned type bar. Each key bar has at its outer extremity a hooked end 35 which holds one end of a restoring spring 35a. The other end of the spring 35a is mounted on a suitable finger 36 forming a portion of the guide comb 33. With this structure, the restoring spring 3512 tends to maintain each key bar in its retracted or normal position, as shown in Fig. 1.

Reference is now made to Figs. 4, 5 and 6 for an explanation in detail of the actuation of a type bar. Actually, Fig. 4 shows the relation of the parts when a key bar is first depressed; Fig. 5 shows the parts just after the type head 14 has struck the platen; Fig. 6 shows the parts after the type head has returned into engagement with the basket 8, with the key bar maintained depressed to a single stroke actuating position; while Fig. 7 shows the arrangement of the parts for repeat operation.

Referring to Fig. 4, key bar 2 is shown depressed to a single stroke position, wherein the operating lug 30 has rotated the plate 6 about stud 23 to effect engagement of the serrated cam tread 15 with the peripheral surface of the drive roller 20. From this position, the cam 5 is driven by the power roll about the stud 16, and the continually increasing radius between stud 16 and the serrated tread 15 forces the stud 16 clockwise about shaft 10, thereby rotating the crank arm 4 to drive the type bar directly until the tail piece 21 hits the control stop 22. At this position, and in the manner hereinbefore described, the serrated tread 15 is disengaged from the peripheral surface of power roll 20, and the spring 17 rotates the cam 5 counterclockwise about stud 16 back to its retracted position, as shown in Fig. 1. In the retracted position, the cam surface 29 engages the car 28 on the plate 6 and holds the latter in a position with its upper edge engaging the car 26 on the crank arm 4, as shown in Fig. 5.

While the type bar 1 is being driven against the platen and then returned to the basket 8, the spring 25 holds the plate 6 upwardly and to the left, Fig. 5, with stud 23 in engagement with the right end peripheral surface of the aperture 24.

If the key bar 2 is held depressed in the single stroke position, as shown in Figs. 5 and 6, then, as the crank arm 4 rotates counterclockwise upon return of the type bar, the key ear 31 will engage the front edge 37 of the lug 30 and thereby prevent a repeat stroke of type bar 1. It follows that plate 6 will be displaced slightly by the lug 30 against the action of the spring 25, as shown in Fig. 6. Because of the tension on spring 25, however, the actuating plate 6 will be restored to its normal position, as shown in Fig. 1, as soon as lug 30 is raised out of engagement with the key ear 31.

With further reference to Fig. 6, if a transverse force is applied to the key car 31 in the direction of the arrow (1" by a projecting portion 52a on said key lever, then the plate 6 will be rotated about stud 23 to actuate the cam 5 for bringing the serrated tread 15 again into engagement with the peripheral surface of the power roll 20.

In order that a key bar 2 may be moved downwardly from the position shown in Fig. 6 to obtain an actuation of the cam 5, the guide slot 34 for the bar is extended to provide a recess 41 (Fig. 2). Arranged within this recess is a spring 42 resting at its lower end upon a pintle 43 and acting at its upper end against an abutment member 44 for holding the latter normally against shoulders 47 at the upper end of the recess. The shoulders 47 are located in the same plane with the bottoms of the slots 34 so that the abutment member 44 is engaged by the key bar when the latter is moved to the position of Fig. 6. While the depression of the type bar is resiliently limited by the member 47, the type bar can be depressed further to a repeat position in opposition to the compression of spring 42. In Fig. 3, the member 44 is illustrated as being notched at 48' and 49 to provide grooves for riding on rails 50, 51which form a part of the wall of the recess 41. Accordingly, the vertical movement of the member 44 is guided by the interelation of the grooves 48, 49 with rails 50, 51.

To provide for the installation of the member 47 in the guide comb, the recess 41 is broadened at a point below the rails 50, 51 to an extent that the member can pass through it and into engagement with rails 50, 51. Spring 42 is then installed between the member 44 and the pintle 43, as shown. This simple construction facilitates the installation of the stud and spring in the guide cage 33. Obviously, if the free length of spring 42 is greater than the depth of the recess 41, the'spring will be preloaded after it has been installed in the guide comb. The preloaded spring will resiliently resist the depression of key bar 2 beyond its normal operating position; i. e. at the normal position of the abutment member 44. With an additional force, however, the key bar can be depressed to compress spring 42, and thus reach a lower or repeat position.

It will be noted that with this construction, the normal operation of the key bar will not be impaired, and yet, by simply exerting a little extra force, the key bar can be depressed to a repeat position. Accordingly, an optionally selectable repeatposition is provided for key bar 2. The typist with a normal or single stroke will depress key bar into engagement with the member 44, but, upon applying additional pressure to the key bar, it can be depressed further against spring 42 into a repeat position.

In order to adapt the key bar 2 for initiating repeat type bar operation when it has been depressed to a repeat position, a repeat lug 52 is positioned contiguous to the operating lug 30. The repeat lug 52 is so positioned that it does not prevent the front edge of the lug 30 from engaging the car 31 after a single type bar stroke. However, when the key bar 2 is depressed beyond its normal or single stroke operating position, and into the repeat position by compressing the spring 42, then the repeat lug 52 acts on the key ear 31 to provide the transverse force in the direction of arrow a required for a repeat key operation, as shown in Fig. 6.

When key bar 2 is depressed to the repeat position shown in Fig. 7, the repeat lug 52 will intercept the key car 31 before it engages the front edge of the lug 30. That is, as the type bar returns to its rest position and the crank arm 4 rotates counterclockwise about shaft 10, the ear 31 on the plate 6 engages a sloped or inclined surface 53 on the repeat lug 52. As the key ear 31 slides up sloped surface 53, the required transverse force is provided in the direction of the arrow a to rotate the operating plate 6 counterclockwise about stud 23, and thereby actuate cam into engagement with the power roll 20. During each complete type bar strokewhile the key bar is held in the repeat position-crank arm 4 will rotate clockwise to that position shown in Fig. 5, and then rotate counterclockwise to the position shown in Fig. 7, whereupon the key ear 31 will slide up the sloped surface 53 of lug 52 to again throw the cam 5 into engagement with the power roll 20.

Through this construction, ingenious yet simple optional repeat and no-repeat key bar action is provided. The typist simply depresses a key bar to its normal stop position for a single stroke, and then for a repeat stroke depresses the key bar against a pre-loaded springthe spring 42, Fig. 3whereupon a repeat lug 52 is positioned for engagement with the key ear 31 to cause continuous repeat strokes of the type bar 1.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art, without departing from the spirit of the invention. It is the inten- 6 tion, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

. 1. In a typewriter having a type bar, a repeat nonrepeat actuating mechanism for said type bar comprising, in combination, means including a crank arm operatively connected to said type bar, a power roll, a cam pivotally mounted upon said crank arm and engageable with said power roll for actuating said crank arm, yieldable means for holding said cam normally in a position free of said power roll, a plate mounted upon said crank arm for both bodily and pivotal movement relative to the latter, said plate operating upon pivotal movement to force said cam into engagement with said power roll, a key lever having a lug operating upon depression of the key lever to impart pivotal movement to said plate, a spring for urging said plate upwardly against the action of said lug, said plate moving with said crank arm upon actuation of the latter by said cam from a position beneath said lug, said spring rocking said plate upwardly when free to a position in which its edge is engageable with the side of said lug if the key lever is held depressed, a projecting portionon said key lever engaging said plate when the latter is raised and the key lever is held in its initial depressed position, said projecting portion operating to rock said cam into engagement with said power roll upon further depression of said key lever, and an inclined surface onsaid key lever engageable by said plate when the latter is raised by said spring and the key lever is held in its further depressed position, said inclined surface operating to move said plate in a direction to engage said cam with said power roll as the plate moves with said crank arm during the return of said type bar to its home position.

2. An improved power operated typewriter comprising, in combination, a type bar, an operating mechanism effectuating the driving of said type bar from a rest position to a print position, a key bar unit movable into engagement with said operating mechanism to actuate the same and thereby effect type bar print strokes, said key bar unit comprising a key bar and means supporting the same for pivotal movement from a rest position to a single stroke position and beyond it in the same direction to a repeat stroke position, said key bar having an operating lug positioned for engagement with said operating mechanism when said key bar is in a single stroke position thereby initiating a single print stroke of said type bar, stop means positioned for engagement with said operating mechanism after a single print stroke and while said key bar is held in a single stroke position, and a repeat lug positioned for engagement with said operating mechanism when said key bar is depressed to a repeat stroke position for continuous repeat strokes of said type bar, said operating lug, said stop means, and said repeat lug all being positioned on said key bar adjacent one another and for engagement with said operating mechanism one at a time, said key bar supporting means comprising a guide cage defining a slot for guiding the pivotal movement of said key bar from a rest position to a single stroke position with said guide cage further defining an aperture opening into one of said slots to receive said key bar for movement beyond said single stroke position to a repeat stroke position, an abutment member positioned for sliding movement in said aperture, and resilient means holding said abutment member normally at the bottom of said slot to limit resiliently the pivotal movement of said key bar to said single stroke position, but permitting depression of said key bar beyond said single stroke position and in opposition to the resistance of said resilient means to a repeat stroke position whereby said key bar is supported for optionally selectable repeat non-repeat type bar action.

3. An improved power operated typewriter comprising, in combination, a type bar, an operating mechanism for driving said type bar from a rest position to a print position, a key bar unit movable into engagement with said operating mechanism to actuate the same and thereby effect type bar print strokes, said key bar unit comprising a key bar, means supporting the same for pivotal movement from a rest position to a single stroke position and beyond it in the same direction to a repeat position, said key bar having juxtapositioned thereon an operating lug positioned for engagement with said operating mechanism when said key bar is depressed to a single stroke position, stop means positioned for engagement with said operating mechanism after a type bar print stroke and while said key bar is held in a single stroke position, and a repeat lug positioned for engagement with said operating mechanism when said key bar is depressed to a repeat stroke position for continuous repeat strokes of said type bar.

4. An improved typewriter comprising, in combination, a type bar, an operating mechanism effectuating the driving of a type bar from a rest position to a print position, a three position key bar unit movable into engagement with said operating mechanism to actuate the same and thereby effect type bar print strokes, and key bar mounting means for controlling the position of the key bar unit and its consequential engagement with said operating mechanism and the resultant actuation of said type bar, said key bar unit comprising a key lever having juxtapositioned thereon an operating lug for initiating a single type bar print stroke when said key is held in its normal operating position, stop means for preventing a repeat stroke of said type bar when said key lever is held in said normal operating position, and a repeat lug for initiating repeat type bar print strokes when said key lever is held depressed beyond said normal operating position and into a repeat position, said operating lug, said stop means and said repeat lug being engageable with said operating mechanism one at a time.

5. An improved typewriter comprising, in combination, a type bar, an operating mechanism eftectuating the driving of said type bar from a rest position to a print position, a three position key bar movable into engagement with said operating mechanism to actuate the same and thereby effect type bar print strokes, and key bar mount ing means for controlling the position of the key bar and its consequential engagement with said operating mechanism and the resultant actuation of said type bar, said key bar mounting means comprising a guide comb defining a slot for guiding the depression of said key bar, said comb further defining a repeat aperture interconnected with said slot to form an extension thereof, an abutment member, and resilient means positioning the same in said repeat aperture with said abutment member being positioned normally to limit resiliently the depression of said key bar to a single stroke position, but to permit depression of said key bar to a repeat position in opposition to said resilient means whereby said key bar is supported for optionally selectable repeat non-repeat type bar action.

References Cited in the file of this patent UNITED STATES PATENTS 1,789,661 Schulze Jan. 20, 1931 2,043,393 Pasinski June 9, 1936 2,188,935 Wittenmyer Feb. 6, 1940 

